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The MatterAttractors plugin, which enables attractors between bodies, has been fixed. The original plugin only worked if the body with the attractor was _first_ in the world bodies list. It can now attract any body, no matter where in the world list it is. Fix phaserjs#5160 
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‎src/physics/matter-js/lib/plugins/MatterAttractors.js‎

Lines changed: 113 additions & 96 deletions
Original file line numberDiff line numberDiff line change
@@ -5,108 +5,125 @@ var Matter = require('../../CustomMain');
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* See the readme for usage and examples.
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* @module MatterAttractors
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*/
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var MatterAttractors = {
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// plugin meta
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name: 'matter-attractors', // PLUGIN_NAME
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version: '0.1.7', // PLUGIN_VERSION
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for: 'matter-js@^0.14.2',
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silent: true, // no console log please
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// installs the plugin where `base` is `Matter`
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// you should not need to call this directly.
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install: function(base) {
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base.after('Body.create', function() {
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MatterAttractors.Body.init(this);
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});
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base.before('Engine.update', function(engine) {
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MatterAttractors.Engine.update(engine);
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});
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},
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Body: {
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/**
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* Initialises the `body` to support attractors.
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* This is called automatically by the plugin.
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* @function MatterAttractors.Body.init
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* @param {Matter.Body} body The body to init.
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* @returns {void} No return value.
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*/
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init: function(body) {
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body.plugin.attractors = body.plugin.attractors || [];
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}
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},
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Engine: {
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/**
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* Applies all attractors for all bodies in the `engine`.
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* This is called automatically by the plugin.
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* @function MatterAttractors.Engine.update
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* @param {Matter.Engine} engine The engine to update.
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* @returns {void} No return value.
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*/
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update: function(engine) {
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var world = engine.world,
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bodies = Matter.Composite.allBodies(world);
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for (var i = 0; i < bodies.length; i += 1) {
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var bodyA = bodies[i],
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attractors = bodyA.plugin.attractors;
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if (attractors && attractors.length > 0) {
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for (var j = i + 1; j < bodies.length; j += 1) {
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var bodyB = bodies[j];
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for (var k = 0; k < attractors.length; k += 1) {
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var attractor = attractors[k],
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forceVector = attractor;
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if (Matter.Common.isFunction(attractor)) {
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forceVector = attractor(bodyA, bodyB);
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}
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if (forceVector) {
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Matter.Body.applyForce(bodyB, bodyB.position, forceVector);
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}
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var MatterAttractors =
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{
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name: 'matter-attractors',
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version: '0.1.7',
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for: 'matter-js@^0.14.2',
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silent: true,
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// installs the plugin where `base` is `Matter`
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// you should not need to call this directly.
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install: function (base)
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{
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base.after('Body.create', function ()
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{
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MatterAttractors.Body.init(this);
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});
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base.before('Engine.update', function (engine)
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{
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MatterAttractors.Engine.update(engine);
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});
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},
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Body:
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{
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/**
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* Initialises the `body` to support attractors.
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* This is called automatically by the plugin.
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* @function MatterAttractors.Body.init
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* @param {Matter.Body} body The body to init.
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* @returns {void} No return value.
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*/
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init: function (body)
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{
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body.plugin.attractors = body.plugin.attractors || [];
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}
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},
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Engine:
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{
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/**
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* Applies all attractors for all bodies in the `engine`.
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* This is called automatically by the plugin.
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* @function MatterAttractors.Engine.update
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* @param {Matter.Engine} engine The engine to update.
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* @returns {void} No return value.
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*/
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update: function (engine)
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{
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var bodies = Matter.Composite.allBodies(engine.world);
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for (var i = 0; i < bodies.length; i++)
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{
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var bodyA = bodies[i];
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var attractors = bodyA.plugin.attractors;
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if (attractors && attractors.length > 0)
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{
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for (var j = 0; j < bodies.length; j++)
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{
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var bodyB = bodies[j];
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if (i !== j)
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{
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for (var k = 0; k < attractors.length; k++)
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{
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var attractor = attractors[k];
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var forceVector = attractor;
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if (Matter.Common.isFunction(attractor))
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{
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forceVector = attractor(bodyA, bodyB);
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}
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if (forceVector)
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{
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Matter.Body.applyForce(bodyB, bodyB.position, forceVector);
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}
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}
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}
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}
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}
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}
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}
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}
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}
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}
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},
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/**
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* Defines some useful common attractor functions that can be used
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* by pushing them to your body's `body.plugin.attractors` array.
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* @namespace MatterAttractors.Attractors
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* @property {number} gravityConstant The gravitational constant used by the gravity attractor.
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*/
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Attractors: {
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gravityConstant: 0.001,
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},
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/**
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* An attractor function that applies Newton's law of gravitation.
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* Use this by pushing `MatterAttractors.Attractors.gravity` to your body's `body.plugin.attractors` array.
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* The gravitational constant defaults to `0.001` which you can change
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* at `MatterAttractors.Attractors.gravityConstant`.
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* @function MatterAttractors.Attractors.gravity
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* @param {Matter.Body} bodyA The first body.
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* @param {Matter.Body} bodyB The second body.
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* @returns {void} No return value.
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* Defines some useful common attractor functions that can be used
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* by pushing them to your body's `body.plugin.attractors` array.
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* @namespace MatterAttractors.Attractors
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* @property {number} gravityConstant The gravitational constant used by the gravity attractor.
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*/
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gravity: function(bodyA, bodyB) {
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// use Newton's law of gravitation
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var bToA = Matter.Vector.sub(bodyB.position, bodyA.position),
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distanceSq = Matter.Vector.magnitudeSquared(bToA) || 0.0001,
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normal = Matter.Vector.normalise(bToA),
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magnitude = -MatterAttractors.Attractors.gravityConstant * (bodyA.mass * bodyB.mass / distanceSq),
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force = Matter.Vector.mult(normal, magnitude);
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// to apply forces to both bodies
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Matter.Body.applyForce(bodyA, bodyA.position, Matter.Vector.neg(force));
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Matter.Body.applyForce(bodyB, bodyB.position, force);
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Attractors:
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{
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gravityConstant: 0.001,
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/**
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* An attractor function that applies Newton's law of gravitation.
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* Use this by pushing `MatterAttractors.Attractors.gravity` to your body's `body.plugin.attractors` array.
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* The gravitational constant defaults to `0.001` which you can change
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* at `MatterAttractors.Attractors.gravityConstant`.
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* @function MatterAttractors.Attractors.gravity
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* @param {Matter.Body} bodyA The first body.
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* @param {Matter.Body} bodyB The second body.
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* @returns {void} No return value.
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*/
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gravity: function (bodyA, bodyB)
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{
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// use Newton's law of gravitation
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var bToA = Matter.Vector.sub(bodyB.position, bodyA.position);
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var distanceSq = Matter.Vector.magnitudeSquared(bToA) || 0.0001;
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var normal = Matter.Vector.normalise(bToA);
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var magnitude = -MatterAttractors.Attractors.gravityConstant * (bodyA.mass * bodyB.mass / distanceSq);
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var force = Matter.Vector.mult(normal, magnitude);
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// to apply forces to both bodies
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Matter.Body.applyForce(bodyA, bodyA.position, Matter.Vector.neg(force));
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Matter.Body.applyForce(bodyB, bodyB.position, force);
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}
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}
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}
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};
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module.exports = MatterAttractors;

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